The document discusses the need for field guides to catalog and classify microbes. Field guides for microbes include information on phylogenetic classification, functional diversity, biogeography, niche and function, and means for identification. They provide a guide for interpreting normal and abnormal microbial states. Field guides are important for understanding emerging pathogens, enzyme discovery, forensic microbiology, climate change, global ecology, antimicrobial resistance, microbiome manipulation, and vaccine design, as microbes play a key role in many areas but are challenging to study due to their small size, diversity, numbers, and inability to culture many species. DNA sequencing, other technological advances, and citizen science projects help advance field guides for microbes.